Over 30% of adults in 12 US states are obese, and 26 of the top 30 most obese states are in the Midwest and South, according to a new study. In 2000, no state had an obesity rate of 30% or more, and in 1990 no state had an obesity rate above 15%.

Individuals with a body mass index (a calculation based on weight and height ratios) of 30 or higher are considered obese, according to the CDC. Using the BMI scale, a 5'5" person would need to weigh at least 180 pounds to be considered obese, and a 5'10" person would need to weigh 209 pounds or more.

"Obesity has contributed to a stunning rise in chronic disease rates and health care costs. It is one of the biggest health crises the country has ever faced," said Jeffrey Levi, PhD, Executive Director of TFAH. "The good news is that we have a growing body of evidence and approaches that we know can help reduce obesity, improve nutrition and increase physical activity based on making healthier choices easier for Americans. The bad news is we’re not investing anywhere near what we need to in order to bend the obesity curve and see the returns in terms of health and savings."

The obesity rates by state in 2011 from highest (1) to lowest (51), and including the District of Columbia, were:

According to the World Health Organization, the United
States has an average national obesity rate of 33.9% making it the ninth most obese country in the world and the most obese "industrialized country" with
second place New Zealand (26.5%) and third place Canada (23.1%) several
percentage points behind.

A study in Health Affairs showed that in 2008 obesity-related medical costs totaled $147 billion a year (nearly 10 percent of total medical spending). The annual medical costs for people who are obese were $1,429 higher than those of normal weight. The majority of the spending is generated from treating obesity-related diseases such as diabetes, according to TFAH.